The present invention relates to an electrotherapy device for providing controlled electrical stimulation to a patient. More particularly, the device comprises circuitry that provides high voltage pulsed current (HVPC) electrical stimulation to reduce pain, and circuitry that provides neuromuscular electrical stimulation (NMS) to re-educate muscular and neural tissues of the patient.
As is known, pain in a patient, especially pain arising from a surgical procedure, may be effectively reduced through the application of high voltage pulsed current (HVPC) electrotherapy. Typically, the therapy involves the use of a device that provides short duration low amperage high voltage constant charge pulses to preselected areas of the patient's tissues through electrical leads or electrodes. The therapy continues for a preselected period of time, and the patient is given the ability to control the peak voltage of the charges delivered so that the charges are received at a comfortable level.
As is also known, electrotherapy may be used after a surgical procedure has been performed in order to re-educate muscular and neural tissues and prevent atrophy thereof. Typically, a neuromuscular stimulator (NMS) device is provided for supplying constant current pulses to muscular and neural tissues of the patient through electrical leads or electrodes. As with the HVPC device, the patient is given the ability to control the amplitude of the current delivered to maintain a comfortable level.
However, the HVPC device and the NMS device have been previously supplied as separate units. Accordingly, a patient recovering from a surgical procedure must first be trained to use an HVPC device in order to control the pain arising from the surgical procedure, and then later must be trained to use an entirely different NMS device in order to re-educate muscle tissue and prevent atrophy. This can prove to be difficult and cumbersome, especially if the devices have disparate operating controls. Therefore, it is highly beneficial to a patient during rehabilitation to be able to use a single stimulating unit to provide both HVPC electrotherapy and NMS electrotherapy.
Previous HVPC devices have operated by allowing a regulated voltage supply to provide a predetermined current flow through a coil for a period of time, and then halting the flow of current. As is well known, a voltage spike results, and the voltage spike has a peak amplitude corresponding to the flow of current halted. However, the regulated voltage supplies used in prior art HVPC devices have relatively low power efficiency, as is known to one skilled in the art. The low power efficiency is especially problematic if the power source providing the input voltage to the voltage regulator is a battery. Consequently, it would be highly desirable to provide an HVPC electrotherapy device that does not use a voltage regulator and yet provides charges having preselected voltage peaks.
It would also be highly desirable to provide an HVPC device that can sense whether a patient is actually electrically connected to an output of the device and is receiving electrotherapy. A problem has arisen in previous HVPC devices in that a patient becomes separated from one or more of the HVPC electrodes, and the patient does not feel any stimulation. In response, the patient increases the intensity of the HVPC output. After discovering that in fact the electrode has fallen off, the patient attempts to re-attach the electrode, and receives a severe shock from the high intensity HVPC output. Thus, it would be advantageous to shut down the output of the HVPC device when the device senses that a patient is not electrically connected. Also, an HVPC device that senses whether a patient is electrically connected would have the further advantage that, if the power source powering the HVPC device is a battery, unnecessary use of a limited power supply would be reduced.